PIA07808: Three Moons Meet

Saturn’s moons Janus and Epimetheus are captured swinging around Saturn’s
rings and past Dione in this movie sequence from the Cassini spacecraft.

The spacecraft repeatedly imaged the two moons just as they were about to
round the outside edge of the rings, which were out of view to the left.
Janus and Epimetheus orbit Saturn at nearly the same distance and
velocity, although (as seen here) Janus is several tens of thousands of
kilometers ahead of Epimetheus and farther from Cassini. Dione is actually
quite far in the background compared to the small moons.

At the beginning of the movie, Epimetheus (116 kilometers, or 72 miles
across) is at the left, Janus (181 kilometers, or 113 miles across) is at
the center, and Dione (1,126 kilometers, or 700 miles across) is at the
right.

The movie was created using 18 clear-filter images taken over a period of
about 30 minutes. The images were acquired by the Cassini spacecraft
narrow-angle camera on Dec. 30, 2005, at a mean distance of approximately
2.3 million kilometers (1.4 million miles) from Janus and 2.3 million
kilometers (1.4 million miles) from Epimetheus. The image scale is
approximately 14 kilometers (9 miles) per pixel on Janus and Epimetheus,
and 16 kilometers (10 miles) per pixel on Dione.

The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory,
a division of the California Institute of Technology in Pasadena, manages
the mission for NASA’s Science Mission Directorate, Washington, D.C. The
Cassini orbiter and its two onboard cameras were designed, developed and
assembled at JPL. The imaging operations center is based at the Space
Science Institute in Boulder, Colo.